Process for making bis diamino alkynes



United States Patent 3,340,259 PROCESS FOR MAKING BIS DIAMINO ALKYNESJames F. Vitcha, New Providence, and George L. Moore, South Plainfield,N.J., assignors, by mesne assignments, to Cumberland ChemicalCorporation, New York, N.Y., a corporation of Delaware No Drawing.Original application Jan. 20, 1961, Ser. No. 90,209, now Patent No.3,268,524, dated Aug. 23, 1966. Divided and this application Mar. 10,1965, Ser. No. 438,755

7 Claims. (Cl. 260-246) This is a division of application Ser. No.90,209, filed Jan. 20, 1961, now US. Patent 3,268,524.

This invention relates to acetylenic nitrogen compounds, moreparticularly diamino alkymes, and to improved methods of preparing suchcompounds.

Although procedures are known for the preparation of nitrogen compoundsof the acetylene series, i.e., nitrogen compounds having tripleunsaturated carbon linkages, by the reaction of amines, acetylene andaldehydes, such procedures have not, in general, proved commerciallyfeasible. The yields in these prior art methods, for example, tend to below, and, moreover, because of the nature of the prior art reactions,side products and by-products are formed to a'considerable extent, andgreat difficulty is experienced in recovering the reaction products.

According to the invention described herein, commercially feasibleprocedures for preparing nitrogen compounds of the acetylene serieswhich avoid or alleviate many of the problems encountered in the priorart have been discovered.

In accordance with the present invention, there have been prepareddiamino butynes having the formula:

In the foregoing formula, R may be an aliphatic, aryl, alkyl aryl oralicyclic hydrocarbon radical; R' may be an aliphatic, aryl, alkyl arylor alicyclic hydrocarbon radical or hydrogen; or the part may representa heterocyclic base, namely, piperidine, morpholine or pyrrolidine.

When R and R are hydrocarbon radicals, these will usually have fewerthan 20 and preferably fewer than carbon atoms in the chain. Typically,R and R may be aliphatic hydrocarbon radicals, such as propyl,isopropyl, n-butyl, isobutyl, tertiary butyl, hexyl, 2-ethyl hexyl,isononyl, n-nonyl, 3,5,5-trimethylpentyl, l,1,3,3-tetramethylbutyl, andthe like, including the isomeric alkyl derivatives thereof. R and R mayalso be alicyclic hydrocarbon radicals, such as cyclopentyl, cyclohexyl,cycloheptyl, cyclooctyl, and so forth. When R and R are aryl or alkylaryl groups, these may have one or more uncondensed benzene nuclei.Preferably, however, R and R have one uncondensed benzene nucleus.Typical of such groups may be mentioned phenyl and its homologues, suchas tolyl, xylyl, and so forth.

In the formula above, R" may be hydrogen or a lower alkyl radical havingup to 6 carbon atoms. Usually R" will be hydrogen, as will be clear fromthe following description.

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As will be more clear from the following description, the groups R, R,or the part in the above formula will correspond to the radicals makingup the primary or secondary amines or cyclic imines used to prepare theacetylenic nitrogen compounds. The group R" will correspond to thehydrocarbon radical making up the carbonyl compounds used in thereactions, or hydrogen.

These and other amino compounds of the acetylene series, i.e., aminocompounds having triple unsaturated carbon linkages, are prepared byreacting amines, including cyclic imines, having at least one activehydrogen attached to the amino nitrogen, aldehydes and acetylene in aninert reaction medium and in the presence of catalysts.

The reaction is carried out in two steps or stages: First, a mono-aminoalkyne is prepared. Then, the acetylene atmosphere is removed,additional aldehyde is charged to the reactor, and the second step orstage is completed by addition of a second portion of the amine, usingthe same conditions as employed in the first step or stage of thereaction. The reaction proceeds stepwise according to the followingequations:

As will be noted, acetylene is a reagent only in the first step.

As catalysts suitable for carrying out the above reactions may bementioned the heavy metals of subgroups IB and 11-13 of the PeriodicTable of elements and their compounds, as, for example, organic andinorganic salts of copper and the other heavy metals of these subgroups,such as the chloride, acetate, formate, and the like. Also may bementioned the acetylides of such heavy metals, for example,acetylene-copper compounds. Other catalysts, such as Adkins Catalyst,i.e., copper-barium chromite, may also be used. Among the catalysts, thecopper salts, and more particularly the cupric salts, are especiallysuitable. Particularly good results are obtained with cupric chloride,and this material is preferred.

The catalysts or mixtures thereof may,'if desired, be used with suitableinert carriers, such as, for example, finely divided alumina,diatomaceous earth, silica, silica gel, kieselguhr, and mixtures of theforegoing.

Primary and secondary amines, as well as cyclic imines, and mixtures ofthe foregoing, are useful in preparing the acetylenic amino compoundsdescribed herein. When aliphatic amines are used, these may be primaryor secondary amines having straight chains or branched chains typified,as partially indicated above, by the following: methyl, ethyl, propyl,isopropyl, n-butyl, isobutyl, tert.butyl, hexyl, Zethylhexyl, isononyl,n-nonyl, 3,5,5-trimethylpentyl, 1,1,3,3-tetramethylbutyl groups and theisomeric alkyl derivatives thereof. When secondary amines are used thehydrocarbon radicals attached to the amino nitrogen may be the same ordifferent. As will be clear from the examples, best results are achievedwith the secondary amines. As examples of the saturated monocyclicheterocyclic amino compounds, or, more properly, cyclic imines, may bementioned morpholine, piperidine and pyrrolidine. Both primary andsecondary aryl or alkyl aryl amines may be used, depending upon the typeof acetylenic amino compounds desired. Of the aryl compounds, thearomatic amines having a single benzene nucleus are preferred. Amongthese may be mentioned aniline, toluidine, xylidine, and the mono-alkylderivatives thereof, such as monomethyl aniline, monoethyl aniline, andother mono-alkyl phenyl amines having up to about carbon atoms in thealkyl group. Typical of the alicyclic amines may be mentionedcyclopentylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine,and the like. Also may be mentioned the mono-substituted alicyclicamines, such as cyclopentyl ethyl amine, cyclohexyl methyl amine, andthe like. When primary and secondary amines are used, these preferablyhave fewer than a total of carbon atoms. Other suitable amines andcyclic imines will readily suggest themselves to those skilled in theart from the foregoing description.

The reaction of the above described amino nitrogen compounds withacetylene and aldehydes is carried out in an inert solvent medium. Careshould be exercised in selecting the solvent to prevent undesirableby-product and side-product formation and to avoid tedious recoveryprocedures. It has also been discovered that the choice of reactionmedium has a significant effect on the yields achieved.

In general, non-polar solvents which are inert to both the startingmaterials and the reaction products and which are readily volatilizablemay be used. Among such solvents, saturated or unsaturated aliphatichydrocarbons which are liquid at atmospheric conditions are especiallysuitable. Preferred for use are saturated aliphatic hydrocarbons having6 to 19 carbon atoms.

The aldehydes suitable for use in the present invention may be describedas simple aldehydes having one carbonyl radical. Although carrying outthe reaction with aldehydes containing more than 1 carbonyl radical isfeasible, in general, the use of such materials causes undesirable sidereactions. Among the particularly important aldehydes may be mentionedformaldehyde, including Formalin (an aqueous solution of about 37percent by weight of formaldehyde) and Methyl Formcel (a solution ofabout 55 percent by weight of formaldehyde in methanol), acetaldehyde,and other simple aldehydes having fewer than about 6 carbon atoms. Theprecursors of formaldehyde, e.g., the cyclic trimer known as trioxan,and the linear polymers of formaldehyde, known as polyoxymethylenes, aswell as the cyclic polymer of acetaldehyde, known as paraldehyde, may beadvantageously employed.

Although any of the above described aldehydes may be used, it has beendiscovered that greatly superior results are obtained in preparingcompounds of the formula described hereinabove when linear polymers offormaldehyde are used. Such polymers are polyoxymethylenes of theformula HOCH O'[CH O],,CH OH, where n is an integer up to 100.Especially good results are obtained when trioxymethylene, which iscommonly referred to as paraformaldehyde, is employed, and this materialis preferred.

The acetylene used in the reaction may be highly concentrated acetylene,or acetylene diluted with foreign gases which are inert to the reaction.Electric arc acetylene, for example, may be used.

The method of contacting the reactants is important. Thus, it has beendiscovered that greatly improved yields are obtained by suspending thealdehyde in an inert nonpolar solvent containing the catalyst,subjecting this reaction medium to an atmosphere comprising acetylene,and adding the amine to the resulting environment.

Care should be taken in adding the amine to avoid the presence of excessunreacted amine in the reaction medium. Thus, too rapid an addition ofthe amine results in decreased yields of desirable products andproduction of by-products, side products and tars. The rate of additionof the amine should be slow enough so as to avoid the presence of excessunreacted amine in the reaction mixture. In general, the rate ofaddition of the amine should be such that at any given time less thanabout 25 mole percent, and preferably less than about 10 mole percent ofunreacted amine is present in the reaction mixture, based upon the molesof unreacted aldehyde in the reaction mixture. The rate of addition ofthe amine, in terms of moles of amine per minute per mole of aldehyde inthe reaction mixture, may vary between about 0.0005 and 0.15, is usuallybetween about 0.005 and 0.015, and is preferably between about 0.0025and 0.030.

The proportion of amine to aldehyde is also important. In general, themolar ratio of amine to aldehyde may vary between about 0.80 and 1.20:1and is preferably between about 1.0 and 1.10:1. When polymers of thealdehydes are employed, the above described molar ratios are based uponmoles of equivalent aldehyde and not moles of the polymers. Whenparaformaldehyde is used, for example, a molar ratio of amine toparaformaldehyde of between about 1.0 and 1.10:1 is preferred, and amolar ratio of about 1.05 :1 is optimum, the molar ratios being based onHCHO.

If desired, the reaction may be carried out under anhydrous conditions,and in some instances, this may be preferable. Any suitable dehydratingagent which is inert to reactants and to the products of reaction may beused to take up the water produced by the reaction. Such dehydratingagents are well understood in the art. As a typical example may bementioned anhydrous sodium sulfate.

The temperature and pressure of reaction should be high enough to causereaction to occur, but below the temperature and pressure at which tarand undesirable side products and by-products form. The temperature ofreaction may vary between about 40 C. and C., or higher, and ispreferably between about 50 C. and 60 C. At the lower part of the range,the reaction appears to be sluggish, while at the upper part of therange, secondary products, as well as side products and tars, tend toform. Although the reaction may be carried out at pressures betweenabout 2 and 40 atmospheres, reaction pressures of between about to 250p.s.i.'g. are especially advantageous, and are preferred.

The invention will be more fully understood from the following examples,which, although illustrative, are not intended to limit the scope of'theinvention, except as such limitations may appear in the claims.

Example 1 The reactor comprises a one-liter, upright, stainless steelautoclave equipped with an agitator, thermocouple well, acetylene gasburette, liquid amine burette, a proportioning pump for the liquid amineburette, and a pres sure regulator for the acetylene gas burette.

Seventy-five grams of anhydrous n-hexane, 59.4 grams of paraformaldehyde(90% trioxy-methylene), which have been dessicated over sodium hydroxidepellets, and 6.02 grams of anhydrous powered cupric chloride are chargedto the autoclave liner. The autoclave is assembled, and pressure testedby purging with nitrogen. The system is then purged with acetylene, bledoif to 25 -p.s.i.g., and then heated to 60 C. Acetylene is then added tobring the pressure up to to p.s.i.g. and maintained at this pressurethroughout the reaction by means of the gas burette and pressureregulator. The acetylene used is purified by passing it through a DryIce trap and activated alumina.

Diethylamine having a boiling point of 55 to 56 C. at 1 atmospherepressure is charged to the amine burette.

The diethylamine is added to the reaction mixture in the autoclave overa period of about three and one-half hours at a uniform rate of about0.65 grams/minute. The proportioning pump is used to insure a uniformrate of addition. The total charge of diethylamine is 137.2 grams. Atthe completion of the amine addition, the reaction is continued until nomore acetylene is taken up. This point is reached approximately one hourafter completion of the diethylamine addition. At the end of this firststage of the reaction, the percent conversion of the diethylaminetoacetylenic amines is 90.1% of theoretical. Of this conversion, an 83.0%yield of propargyl diethylamine and a 7.1% yield of bis(diethylamino)butyne are achieved. The acetylene atmosphere is removed and anadditional charge of 59.5 grams of paraformaldehyde is charged to thereactor. An additional 137.2 grams of diethylamine is then added to thereactor at a uniform rate, which is controlled by the proportioningpump. It should be noted that in this procedure, acetylene is a reagentonly in the first step. The mixture is then cooled and discharged fromthe autoclave.

The mixture is filtered through a medium sintered glass Buchner funnel.The small filter cake obtained is washed once with a small portion ofn-hexane and the filter cake is discarded. Caution is necessary toinsure that the filter cake is not allowed to dry. After washing, dilutehydrochloric acid is added immediately to destroy any copper acetylidepresent.

A small water layer which appears in the filtrate is separated anddiscarded.

The hexane layer is then distilled through a small Vigreux column underreduced pressure with the pressure being lowered gradually as thedistillation progresses. A nitrogen atmosphere is maintained during thedistillation. The conversion to 1,4-bis(diethylamino)-2-butyne iscomparable to the yield of propargyl diethyl amine achieved in the firststage of the reaction. The amount of diethylamine recovered indicatesthat the diethylamine has combined in practically stoichiometn'cproportions with the paraformaldehyde.

Example 2 Example 1 is repeated, with the exception that morpholine issubstituted for diethylamine. Comparable results are achieved, the mainproduct being 1,4-bis(morpholine)- Z-butyne.

Example 3 For comparison purposes, the first stage of Example 1 isrepeated, with the exception that Formalin (a 37% by weight aqueoussolution of formaldehyde) is used in place of the n-hexane andparaformaldehyde. The yield of propargyl diethylamine is 59.5% oftheoretical, and the yield of bis(diethylamino) butyene is 6.1% oftheoretical, for a total yield of acetylenic amines of 65.6%, which isconsiderably below that obtained in Example 1 at the end of the firststage.

Example 4 For comparison purposes, the first stage of Example 1 is againrepeated, with the exception that Methyl Formcel (a 55% solution offormaldehyde in methanol) is used in place of n-hexane andparaformaldehyde. Other conditions are identical to those of Example 1.A 49.5% conversion to amino propyne and a 2.3% conversion to diaminobutyne are achieved at the end of the first stage.

Example 5 The first stage of Example 1 is again repeated, with theexception that the ratio of diethylamine and paraformaldehyde ton-hexane and catalysts was doubled. Yields comparable to those at theend of the first stage of Example 1 are obtained.

Example 6 The first stage of Example 1 is repeated, with the exceptionthat dibutylamine is substituted for diethylamine.

Yields of propargyl dibutyl amine and bis(dibutylamino) butynecomparable to the yields indicated at the end of the first stage inExample 1 are obtained.

Example 7 The first stage of Example 1 is repeated, with the exceptionthat dimethylamine is substituted for diethylamine. Yields of propargyldimethylamine and bis(dimethylamino) butyne comparable to the yieldsindicated in Example 1 are obtained, at the end of the first stage.

Example 8 The first stage of Example 1 is repeated, with the exceptionthat the cyclic imine, morpholine, is substituted for diethylamine.Yields of 8.3% bis(morpholino) butyne and 72. 6% of N-propargylmorpholine, for a total yield of 80.9% of acetylenic amino compounds atthe end of the first stage are achieved.

Example 9 The first stage of Example 1 is repeated, with the exceptionthat pyrrolidine is substituted for diethylamine. Yields ofbis(pyrrolidino) butyne and N-propargyl pyrrolidine comparable to theyields indicated in Example 8 are achieved.

Example 10 The first stage of Example 1 is repeated, with the exceptionthat piperidine is substituted for diethylamine. Yields ofbis(piperidino) butyne and N-propargyl piperidine comparable to theyields indicated in Example 8 are achieved.

Example 11 Using the first stage procedure described in Example 1,N-ethylaniline is reacted with acetylene and paraformaldehyde in thepresence of a cupric chloride catalyst and a n-hexane reaction medium ata temperature of 75 C. High yields of the interesting aromatic propyne,N-propargyl-N-ethylaniline are obtained at the end of the first stage.

The acetylenic amino nitrogen compounds described herein are valuableinitial materials for the preparation of solvents, pharmaceuticals anddyestuffs. By themselves the acetylenic amino nitrogen compounds areeffective corrosion inhibitors. Condensation products made therefrom areuseful as pickling inhibitors, and the materials themselves may also beused as high energy fuels.

The invention in its broadest aspects is not limited to the specificcompositions, steps and methods described, but departures may be madetherefrom within the scope of the accompanying claims without departingfrom the principles of the invention and without sacrificing its chiefadvantages.

We claim:

1. A process which comprises forming an anhydrous mixture ofparaformaldehyde, a hydrocarbon solvent, and a catalyst selected fromthe group consisting of salts and acetylides of copper, adding anatmosphere of acetylene on said mixture, and gradually adding to saidmixture an amine selected from the group consisting of primary aminesand secondary amines having up to 20 carbon atoms, said amines beingselected from the group consisting of alkyl amines, cycloalkyl aminessaturated monocyclic heterocyclic amines and monocyclic aromatic amines,and mixtures of the foregoing, said amine being added to said mixture ata uniform rate and at a temperature and pressure high enough to causereaction to occur, continuing the reaction until substantially noacetylene is taken up by the reaction mixture, removing the acetyleneatmosphere, charging additional paraformaldehyde to the mixture andadding additional amounts of said amine, the rate of addition of saidamine being such that substantially no excess of unreacted amine ispresent in the reaction mixtures.

2. The method of claim 1, wherein the amount of unreacted amine in thereaction mixture is less than about 25 mole percent based upon the molesof unreacted paraformaldehyde present in said mixture.

3. The method of claim 1, wherein the mole rate of addition of the amineper minute per mole of paraformaldehyde in the reaction mixture isbetween about 0.0005 and 0.15.

4. The method of claim 1, wherein the temperature is between about 40and 90 C. and the pressure is between about 2 and 40 atmospheres.

5. The method of claim 1, wherein the catalyst is cupric chloride.

6. The method of claim 1, wherein enough of said amine is added toprovide a molar ratio of said amine to paraformaldehyde of between about1 and 1.121, said ratio being based upon HCHO.

7. A process which comprises forming an anhydrous mixture ofparaformaldehyde, a hydrocarbon solvent, and a catalyst selected fromthe group consisting of salts and acetylides of copper, adding anatmosphere of acetylene on said mixture, and gradually adding to saidmixture an amine selected from the group consisting of primary aminesand secondary amines having up to 20 carbon atoms, said amines beingselected from the group consisting of alkyl amines, cycloalkyl aminessaturated monocyclic heterocyclic amines, monocyclic aromatic amines,and mixtures of the foregoing, said amine being added to said mixture ata uniform rate and at a' temperature and pressure high enough to causereaction to occur, continuing the reaction until substantially noacetylene is taken up by the reaction mixture, removing the acetyleneatmosphere, charging additional paraformaldehyde to the mixture andadding additional amounts of said amine, the rate of addition of saidamine being such that substantially no excess of said unreacted amine ispresent in said reaction mixture, the amount of unreacted amine in thereaction mixture being less than about 25 mole percent based upon themoles of unreacted paraformaldehyde present in said mixture, the rate ofaddition of the amine per minute per mole of paraformaldehyde in thereaction mixture being between about 0.0005 and 0.15, the temperaturebeing between about 40 and C. and the pressure being between about 2 and40 atmospheres, and the hydrocarbon solvent being a saturatedhydrocarbon having 5 to 19 carbon atoms.

No references cited.

ALEX MAZEL, Primary Examiner.

J. TOVAR, Assistant Examiner.

1. A PROCESS WHICH COMPRISES FORMING AN ANHYDROUS MIXTURE OFPARAFORMALDEHYDE, A HYDROCARBON SOLVENT, AND A CATALYST SELECTED FROMTHE GROUP CONSISTING OF SALTS AND ACETYLIDES OF COPPER,ADDING ANATMOSPHERE OF ACETYLENE ON SAID MIXTURE, AND GRADUALLY ADDING TO SAIDMIXTURE AN AMINE SELECTED FROM THE GROUP CONSISTING OF PRIMARY AMINESAND SECONDARY AMINES HAVING UP TO 20 CARBON ATOMS, SAID AMINES BEINGSELECTED FROM THE GROUP CONSISTING OF ALKYL AMINES, CYCLOALKYL AMINESSATURATED MONOCYCLIC HETEROCYCLIC AMINES AND MONOCYCLIC AROMATIC AMINES,AND MIXTURES OF THE FOREGOING, SAID AMINE BEING ADDED TO SAID MIXTURE ATA UNIFORM RATE AND AT A TEMPERATURE AND PRESSURE HIGH ENOUGH TO CAUSEREACTION TO OCCUR, CONTINUING THE REACTION UNTIL SUBSTANTIALLY NOACETYLENE IS TAKEN UP BY THE REACTION MIXTURE, REMOVING THE ACETYLENEATMOSPHERE, CHARGING ADDITIONAL PARAFORMALDEHYDE TO THE MIXTURE ANDADDING ADDITIONAL AMOUNTS OF SAID AMINE, THE RATE OF ADDITION OF SAIDAMINE BEING SUCH THAT SUBSTANTIALLY NO EXCESS OF UNREACTED AMINE ISPRESENT IN THE REACTION MIXTURES.